H-ARAIM Horizontal Protection Level Optimization via Dynamic Fault Subsets
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Solution Overview
Problem
The existing H-ARAIM system faces challenges in efficiently calculating horizontal protection levels due to unreasonable fault subset classification, increased calculation load with multiple visible satellites, and low accuracy in protection level estimation, which affects the reliability and speed of fault detection and integrity monitoring in multi-constellation GNSS environments.
Innovation Solution
The proposed H-ARAIM system optimizes horizontal protection levels by using a ground reference station and an aircraft with a receiver and data processor to calculate pseudo-range error diagonal covariance matrices, allocate continuity and integrity risks, and employ a gradient ascent method for precise protection level calculation, reducing computational complexity and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the existing ARAIM fault detection model is used with multi-constellation satellites, then the number of visible satellites increases, but the calculation load increases in folds making availability prediction slow
Solution Approach 1:
The patent segments the fault detection process into two stages: first performing constellation layer fault detection to identify faulty constellations, then performing orbital plane layer fault detection only for affected constellations. This hierarchical segmentation reduces the total number of subset calculations from exponential growth to manageable levels, enabling fast availability prediction even with many visible satellites across multiple constellations.
Solution Approach 2:
The patent implements dynamic fault subset classification that adapts to the actual satellite geometry and signal conditions. The system dynamically determines which constellations and orbital planes require detailed subset analysis based on real-time quality indicators, rather than uniformly processing all possible subsets. This dynamic approach optimizes calculation resources and improves processing speed.
2Device complexity
If risks are averagely allocated to each fault subset in existing H-ARAIM, then the protection level calculation is simplified, but the protection level estimation accuracy is low and cannot support development requirements
Solution Approach 1:
The patent applies local quality by allocating integrity risks non-uniformly across different fault subsets based on their actual contribution to horizontal positioning accuracy. Each fault subset receives a risk allocation proportional to its impact on the protection level, rather than equal allocation. This localized risk allocation optimizes the protection level estimation accuracy for each specific fault scenario while maintaining overall system integrity.
3Reliability
If the bound between detection threshold sum and subset solution covariance error is made large enough, then the navigation integrity is ensured, but the protection level becomes conservative and reduces system availability
Solution Approach 1:
The patent changes the parameter of risk allocation from uniform to non-uniform distribution across fault subsets. By adjusting the risk allocation parameters based on each subset's actual impact on positioning accuracy, the system achieves tighter (less conservative) protection levels that maintain navigation integrity while improving system availability. This parameter optimization allows the bound to be sufficiently large for integrity without being excessively conservative.
Data Source
AI summary
An H-ARAIM system of optimizing a horizontal protection level includes constellations, a ground reference station and an aircraft, the ground reference station is used for receiving the satellite coordinate data of the constellations, and processing the received satellite coordinate data into an input data for the calculation of the aircraft horizontal protection level. The aircraft is built-in with a receiver and a data processor, the receiver is used for receiving the input data sent by the ground reference station, and transmitting the input data to the data processor for the data processing as follows: when a difference between a positioning solution of a full visible satellite and a positioning solution of a fault subset is within a threshold of a fault subset monitor system statistical magnitude, the receiver begins to calculate the protection level, which is calculated for protecting the iterative update.